1. Field of the Invention
This invention generally relates to a driver device providing multiple resolution modes for a display device, and more particularly to a multi-resolution driver device for a liquid crystal display panel.
2. Description of Related Art
A still picture comprises of a plurality of small dots representing different shades with density variation of dots. During printing picture process, silver nitrate is used to display the shades of each dot. Hence, when a picture is photoengraved, it is distinct that the printed picture consists of a plurality of small dots. Those small dots are so-call pixels. Re-transmitting and rearranging a plurality of pixels, the original image is reproduced accordingly. The quality of the picture is represented by the image resolution, or definition, which relies on a number of pixels. The number of the pixels is usually calculated by dots per inch. The more pixels in a frame, the better quality of the picture. Hence, when a picture having a particular size consists of more pixels, the image resolution is higher and the reproduced image provides more detailed information.
Since flat panel displays, e.g., liquid crystal display (LCD) and plasma display, provide better resolution and lower power consumption than the traditional Cathode Ray Tube (CRT) display, they become substitutes for the CRT display nowadays. While LCDs always serve as displays for laptop/notebook computers, they serve as displays for desktop computers as well; even the LCD panels are highly priced. Current LCD panel adopts active matrix design such as Thin Film Transistor (TFT) technology, which is one-to-one design; i.e., one thin film transistor corresponds to one pixel. The advantage of the active matrix design is that it only requires a small current flow for the horizontal and vertical grids, so that the pixels can be turned on/off relatively quickly. The TFT LCD comprises an optically anisotropic liquid crystal layer, which transmit the amount of the incoming light based on the strength of the electrical field, thereby acquiring corresponding pixels to the image information.
An LCD also includes an interface circuit transforming analog signals from a host system to digital signals in order to drive the pixels in the LCD. Because the resolution of the LCD depends on the number of the pixels in the active display area, the LCD has to be operated under defined display mode. For instance, in order to display a Video Graphic Array (VGA) image, the active display area has to configure 640*480 pixels. In order to display a Quarter Video Graphic Array (QVGA) image, the active display area has to configure a quarter pixels of the VGA mode, i.e. 320*240 pixels. In order to display a super video graphic array (SVGA) image, the active display area has to configure 800*600 pixels; and in order to display an extended Graphic Array (XGA) image, the active display area has to be configured 1024*768 pixels. Hence, it is desirable to configure a LCD display with multiple resolution modes to accommodate a variety of available resolutions, where frequently used QVGA and VGA modes are particularly desirable.